Concentrations, sources and exposure to metals in dust from automobile mechanic workshops in Nigeria

Background

Dust is ubiquitous and humans are unavoidably in constant contact with it. Therefore, exposure to metal-laden dust from workplaces can be a serious threat to human health.

Objective

The objective of this study was to assess the concentrations of nine metals, namely, Cd, Pb, Cr, Ni Cu, Co, Mn, Zn and Fe, in dust from automobile mechanic workshops (AMWs) in urban and semi-urban areas of Delta State, Nigeria.

Methods

The dust samples were digested in aqua-regia and their metal content was determined by atomic absorption spectrometry.

Results

The concentrations of metals (mg kg^-1) in dust from the AMWs ranged from 0.12 to 4.20 for Cd, 11.3 to 3900 for Pb, 9.05 to 45.3 for Cr, 0.35 to 345 for Ni, 170 to 56,400 for Cu, 1.05 to 31.4 for Co, 51.3 to 310 for Mn, 143 to 634 for Zn, and 70,900 to 258,000 for Fe. The pollution indices indicated that Cd, Cu, Pb and Zn were the prominent contaminants in dust from the AMWs. Children's exposure to metal-laden dust from the AMWs could elicit adverse non-carcinogenic health effects. The carcinogenic risk values obtained for human exposure to metals in dust from the AMWs were above the safe level indicating possible induction of cancer or cancer-related illnesses. The sources of metals in dust from the AMWs are related to automobile emissions and discharges from vehicular components.

Conclusion

The activities in AMWs are potent sources of metals to the environment, especially Cd, Cu, Pb and Zn. Therefore, this study recommends regulatory control of activities conducted in AMWs so as to minimize widespread metal contamination and the consequent impact of metals in the affected dust on humans and the environment.